Bio-Efficacy of Spinetoram 6% W/V (5.66% W/W) + Methoxyfenozide 30% W/V (28.3% W/W) SC against Pod Borers Infesting Greengram [Vigna radiata (L.) Wilczek

Abstract

Background: Spotted pod borer, Maruca vitrata (F.) and blue butterfly, Lampides boeticus (L.) are important lepidopteran borers infesting greengram [Vigna radiata (L.) Wilczek] throughout India. Therefore, novel insecticide mixture in comparison with other standard synthetic insecticides has been tested for its bio-efficacy against these two borers in greengram. Methods: A field experiment was conducted at Vagurani, Usilampatti Block, Madurai district, Tamil Nadu during June to August, 2020 in randomized block design (RBD) with eight treatments and three replications. The experimental field was monitored for the population of pests and natural enemies (No./ 10 plants), per cent pod damage, total grain yield and phyto-toxic symptoms. From the data recorded, per cent reduction in population over control was calculated. The per cent pod damage was calculated by randomly picking 100 pods from each plot of each replication. The grain yield from each plot was recorded after each picking and converted into kg/ ha. Result: Two sprays of spinetoram 6% w/v + methoxyfenozide 30% w/v SC @ 144 g a.i/ha and flubendiamide 34.35 SC @ 48 g a.i/ha from 45 DAS at 15 days interval proved to be most effective and superior in reducing the lepidopteran pod borers like M. vitrata and L. boeticus and no lethal effect was recorded towards the coccinellid predators, Menochilus sexmaculatus, C. transversalis and spiders. This combination did not cause any phytotoxic symptoms like leaf injury, wilting, vein clearing, necrosis, epinasty and hyponasty at any day after treatment on stems, leaves, flowers and pods of greengram.